GQL-12: Added support for generating mutation operations

- Added the Mutation class
- Added tests for the mutation class
- Modified the query class to accomodate the introduction of the Mutation

Author: mghoneimy

src/Mutation.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace GraphQL;
+
+/**
+ * Class Mutation
+ *
+ * @package GraphQL
+ */
+class Mutation extends Query
+{
+    /**
+     * Stores the name of the type of the operation to be executed on the GraphQL server
+     *
+     * @var string
+     */
+    protected const OPERATION_TYPE = 'mutation';
+}

src/Query.php

@@ -18,7 +18,14 @@ class Query
      *
      * @var string
      */
-    private const QUERY_FORMAT = "%s%s {\n%s\n}";
+    protected const QUERY_FORMAT = "%s%s {\n%s\n}";
+
+    /**
+     * Stores the name of the type of the operation to be executed on the GraphQL server
+     *
+     * @var string
+     */
+    protected const OPERATION_TYPE = 'query';
 
     /**
      * Stores the object being queried for
@@ -181,8 +188,8 @@ protected function constructSelectionSet(): string
     public function __toString()
     {
         $queryFormat = static::QUERY_FORMAT;
-        if (!$this->isNested && $this->object !== 'query') {
-            $queryFormat = "query {\n" . static::QUERY_FORMAT . "\n}";
+        if (!$this->isNested && $this->object !== static::OPERATION_TYPE) {
+            $queryFormat = static::OPERATION_TYPE . " {\n" . static::QUERY_FORMAT . "\n}";
         }
         $argumentsString    = $this->constructArguments();
         $selectionSetString = $this->constructSelectionSet();

tests/MutationTest.php

@@ -0,0 +1,94 @@
+<?php
+
+namespace GraphQL\Tests;
+
+use GraphQL\Mutation;
+use PHPUnit\Framework\TestCase;
+
+class MutationTest extends TestCase
+{
+    /**
+     *
+     */
+    public function testMutationWithoutOperationType()
+    {
+        $mutation = new Mutation('createObject');
+
+        $this->assertEquals(
+            'mutation {
+createObject {
+
+}
+}',
+            (string) $mutation
+        );
+    }
+
+    /**
+     *
+     */
+    public function testMutationWithOperationType()
+    {
+        $mutation = new Mutation('mutation');
+
+        $this->assertEquals(
+            'mutation {
+
+}',
+            (string) $mutation
+        );
+    }
+
+    /**
+     * 
+     */
+    public function testMutationWithFields()
+    {
+        $mutation = (new Mutation('createObject'))
+            ->setSelectionSet(
+                [
+                    'fieldOne',
+                    'fieldTwo',
+                ]
+            );
+
+        $this->assertEquals(
+            'mutation {
+createObject {
+fieldOne
+fieldTwo
+}
+}',
+            (string) $mutation
+        );
+    }
+
+    /**
+     *
+     */
+    public function testMutationWithArgumentsAndFields()
+    {
+        $mutation = (new Mutation('createObject'))
+            ->setSelectionSet(
+                [
+                    'fieldOne',
+                    'fieldTwo',
+                ]
+            )->setArguments(
+                [
+                    'argOne' => 1,
+                    'argTwo' => 'val'
+                ]
+            );
+
+        $this->assertEquals(
+            'mutation {
+createObject(argOne: 1 argTwo: "val") {
+fieldOne
+fieldTwo
+}
+}',
+            (string) $mutation
+        );
+    }
+}

tests/QueryTest.php

@@ -46,7 +46,7 @@ public function testEmptyArguments(Query $query)
     /**
      * @covers \GraphQL\Query::__toString
      */
-    public function testExplicitQueryObject()
+    public function testQueryWithOperationType()
     {
         $query = new Query('query');